Simulation of the beam halo from the beam-beam interaction.

A technique for simulating the beam halo in circular [ital e][sup +][ital e[minus]] colliders is introduced, tested, and applied. Amplitude space is divided into core and halo regions, and only halo particles are tracked saving a factor of 100 or more in CPU time. The methods for determining the regions, selecting and tracking particles, and connecting the core and halo are described. Results agree with conventional simulations. The beam halo is strongly influenced by nonlinear beam-beam resonances indicating that resonance streaming and phase convection are the dominant mechanisms for particles reaching large amplitudes.